Liquid meter



NOV. 30, 1965 DOUGLAS 3,220,257

LIQUID METER Filed Feb. 19, 1963 2 Sheets-Sheet 1 +3 FIG 4 O 23 O 1 i I Q 2/ f 9 25 mm? 35 I 20 3/ 7 /3 R1775 0F FLOW Fl Z M z INVENTOR.

Nov. 30, 1965 R. R. DOUGLAS LIQUID METER 2 Sheets-Sheet 2 Filed Feb. 19, 1963 IN V EN TOR.

United States Patent corporation of Delaware Filed Feb. 19, 1963, Ser. No. 259,645 Claims. (Cl. 73-451) This invention is a free piston liquid meter in which the registration is proportional to the number of strokes of the piston. The stroke of the piston is controlled by a reversing valve constructed to maintain the meter accuracy from minimum to maximum flow.

In the drawing, FIG. 1 is a plan view of the meter with the top cover removed, FIG. 2 is a section on line 22 of FIG. 1, FIG. 3 is a section on line 33 of FIG. 1, FIG. 4 is a performance diagram, FIG. 5 is a diagrammatic view illustrating the operation of the valve shifting mec anism, FIG. 6 is a section on line 6-6 of FIG. 5, and FIG. 7 is a view of the valve in its intermediate position.

In the accompanying drawings, 1 indicates the liquid inlet, 2 the liquid outlet, 3 the meter body, 4 the top cover defining a chamber 4a, and 5 the bottom cover defining a chamber 5a. The entire meter casing from inlet to outlet is filled with liquid and the flow is controlled by a valve having a sleeve 6 with inlet ports 7 and 8 and an outlet port 9. At the center of the sleeve is a valve member 10 having a way 11 communicating with the chamber 411 and a way 12 communicating with the chamber 5a. The uppermost position of the valve member is determined by an O-ring which serves as a stop.

In the uppermost position of the valve member 10 (FIG. 2), a port 13 extending crosswise of the valve member and intersecting the way 11 communicates with the inlet port 7 and allows liquid to flow from the inlet 1 through the ports 7 and 13 and way 11 into the chamber 4a. In this position, liquid flows out from the chamber 5a through way 12, and ports 14 and 9.

In the lowermost position of the valve member an O-ring 16 engages the upper end of the sleeve 6 and positions the valve member so that liquid flows in through ports 8 and 14 to way 12 which leads to the lower chamber 5a and flows from the upper chamber 4a through way 11 and ports 13 and 9.

In the uppermost position of the valve member 10, liquid flows from the inlet 1 into the upper chamber 4a and from the lower chamber 5a to the outlet 2. In the lowermost position of the valve member, liquid flows from the inlet 1 into the lower chamber 5a and from the upper chamber 411 to the outlet 2. This flow actuates a free piston 17 reciprocable in a cylinder 18 in the body 3. The piston has discs 19 and 20 of flexible material respectively having flanges 19a and 20a engaging the walls of the cylinder 18 and providing a liquid tight seal in the upward and downward directions of motion of the piston. Fixed to the piston are vertical guide rods 21 and 22 slidzable through a plate 23 fixed to the top of the body 3.

It is necessary that the valve member 10 be shifted or reversed at the end of each stroke of the piston. The shifting of the valve is through a bell crank lever 24 pivoted at 25 on a bracket 26 fixed to the meter body 3. The arm 27 of the bell crank lever (FIG. 1, FIG. 5) has an offset portion 28 provided with a pin and slot connection 29 to the upper end of the valve member 10. The other arm 30 (FIG. 5) of the bell crank lever has a projection 31 which cooperates with a projection 32 on the rod 21 fixed to the piston. A bar spring 33 extends between and is fixed at opposite ends to the piston rod 21 and to the otfset 28 of the bell crank lever 24. Referring now to FIG. 5, as the piston 17 is moving downward in the direction of the arrow 34, the valve member 10 remains in the uppermost position because the projection 31 on the bell crank lever 24 engages and is blocked by the projection 32 on the piston rod 21. This results in bending or stressing the spring 33 and the building up of a force in the direction of arrow 35 on the offset 28 and also-a force in the direction of arrow 36 on the projection 31. As soon as the projection 32 moves low enough so that its upper edge is clear of the projection 31, the stored force in the spring moves the valve member downward in the direction of the arrow 35 until the further down- -ward travel is limited by the stop 16. At the same time that the valve member 10 is moving downward, the projection 31 on the bell crank lever 24 is moving from the right hand side of the projection 32, as viewed in FIG. 5, to the left hand side of the projection. Shifting the valve member 10 downward reverses the flow and causes the piston 17 to move upward, thereby building up a force in the opposite direction to arrow 35 so that at the end of the upward travel of the pistion, the valve member 10 will be shifted back to the uppermost position illustrated in FIGS. 2, 3 and 5. The stroke of the piston to produce reversal of the valve is determined by the length of the projections 31 and 32. Until the stroke of the piston equals the sum of the length of these projections, the valve remains in its last position. At the end of each stroke, the valve is snapped quickly to the new position, thereby reversing the flow and causing a reversal of the direction of movement of the piston. The number of strokes of the piston 17 is a measure of the quantity of the liquid.

The number of piston strokes is counted by a ratchet 37 driving a register 38. Fixed to the upper end of the piston rod 21 is a yoke 39 carrying a pawl 40 which moves the ratchet one tooth counter clockwise during the upstroke of the piston and a pawl 41 which moves the ratchet one tooth in the same direction during the downstroke of the piston. This structure is diagrammatically illustrated because it is well known.

During reversal, the valve member 10 passes through the intermediate position illustrated in FIG. 7. In this position, the ports 7 and 8 communicate with the ports 13 and 14 which in turn discharge through the port 9. This means that the flow is not completely interrupted during the valve reversal. This also has the further advantage of increasing the accuracy of the meter, as explained below.

In the standard liquid meter, the accuracy is represented by the solid line curve 42 in FIG. 4. In the meter of this application, the accuracy is indicated by the dotted line curve 43, which is a substantial improvement at low rates of flow where the standard liquid meters have the poorest accuracy.

In the standard meter, the accuracy is expressed by the following equation:

By way of contrast, the accuracy of the present meter is indicated by the following equation:

Accuracy:

Accuracy:

Where A comparison of these equations shows that in the standard meter, as the rate of flow decreases, the accuracy decreases because the effect of leakage becomes more dominant. In the present meter, while the effect of leakage remains, there are other effects related to the valve travel time which cancel out the effect of leakage at low rates of flow and thereby improve the accuracy. Valve travel (V is essentially constant at all rates of flow (R). The term f RV D denotes the effect of piston over travel during the time required for valve reversal. The term f RV denotes the effect of liquid flowing through the valve member in the FIG. 7 position. This flow does not influence the piston because it goes directly from inlet to outlet.

What is claimed as new is:

1. A liquid meter having a body with an inlet, an outlet and a free piston in the fiow path between the inlet and outlet, said piston having a piston rod carrying a stop, a reversing valve movable to successive positions for reversing the fioW to the piston, said valve having between said positions ports providing a direct connection from the inlet to the outlet, a valve operator slidable in the body parallel to the piston rod, a bell crank pivoted on the body having one arm connected to the valve operator and the other arm having a projection presented toward said stop and riding off the upper and lower edges of the stop respectively at the lower and upper ends of the piston stroke, a bar spring extending between and fixed at opposite ends to said valve operator and said piston rod and bent by the movement of the piston rod relative to the valve operator to build up a force for shifting the valve operator at the end of each stroke and thereby reversing the flow to the piston, and means actuated by the piston for counting the piston strokes and thereby determining the volume of liquid flowing through the meter.

2. A liquid meter comprising a body having a cylinder open at both ends, means providing a first liquid filled chamber communicating with one end of the cylinder, means providing a second liquid filled chamber communieating with said other end of the cylinder, a valve member slidable in the body parallel to the piston and having one end presented to said first chamber and the other end presented to said second chamber, said valve member having between its ends two longitudinally spaced crosswise extending ports and a port extending from said one end of the valve member to one of the crosswise ports, a port extending from said other end of the valve member to the other crosswise port, two longitudinally spaced inlet ways presented toward said valve member, an outlet Way presented toward said valve member intermediate said inlet ways, said valve member being movable to a first position in which one of the inlet ports registers with one of the crosswise ports so liquid fiows into said first chamber and the outlet port registers with the other of the crosswise ports so liquid flows out of said second chamber and said valve member being movable to a second position in which the other of the inlet ports registers with the other ofthe crosswise ports so liquid flows into said second chamber and the outlet port registers with said one crosswise port so liquid flows out of said first chamber, a free piston in said cylinder having a rod with a stop thereon, a bell crank lever pivoted on said body having one arm connected to said valve member and the other arm having a projection presented toward said stop on the piston rod and riding off the upper and lower edges of the stop respectively at the lower and upper ends of the piston stroke, a bar spring connected between said valve member and said piston rod and bent by movement of the piston rod relative to the valve member to build up a force shifting the valve member at the end of each piston stroke and thereby reversing the flow to the piston, and means for counting the piston strokes and thereby determining the volume of liquid fiowing through the meter.

3. A liquid meter comprising a body having a cylinder open at both ends, means providing a first liquid filled chamber communicating with one end of the cylinder, means providing a second liquid filled chamber communicating with said other end of the cylinder, a slide valve member having one end presented to said first chamber and the other end presented to said second chamber, said valve member having between its ends two longitudinally spaced crosswise extending ports and a port extending longitudinally from said one end of the valve member to one of the crosswise ports, a port extending longitudinally from said other end of the valve member to the other crosswise port, two longitudinally spaced inlet ways presented toward said valve member, an outlet way presented toward said valve member intermediate said inlet ways, said valve member being movable to a first position in which one of the inlet ports registers with one of the crosswise ports so liquid flows into said first chamber and the outlet port registers with the other of the crosswise ports so liquid flows out of said second chamber and said valve member being movable to a second position in which the other of the inlet ports registers with the other of the crosswise ports so liquid fiows into said second chamber and the outlet port registers with said one crosswise port so liquid flows out of said first chamber, said inlet and crosswise ports communicating directly with the outlet port while the valvemember is between said first and second positions, a free piston in said cylinder having a rod with a stop thereon, a bell crank lever pivoted on said body having one arm connected to said valve member and the other arm having a projection presented toward said stop on the piston rod and riding off the upper and lower edges of the stop respectively at the lower and upper ends of the piston stroke, a bar spring connected between said valve member and said piston rod and bent by movement of the piston rod relative to the valve member to build up a force shifting the valve member at the end of each piston stroke and thereby reversing the flow to the piston, and means for counting the piston strokes and thereby determining the volume of liquid flowing through the meter.

4. A liquid meter comprising a body having a cylinder open at both ends, means providing a first liquid filled chamber communicating with one end of the cylinder, means providing a second liquid filled chamber communicating with said other end of the cylinder, a slide valve member having one end presented to said first chamber and the other end presented to said second chamber, said valve member having between its ends two longitudinally spaced crosswise extending ports and a port extending longitudinally from said one end of the valve member to one of the crosswise ports, a port extending longitudinally from said other end of the valve member to the other crosswise port, two longitudinally spaced inlet ways presented toward said valve member, an outlet way presented toward said valve member intermediate said inlet ways, said valve member being movable to a first position in which one of the inlet ports registers with one of the crosswise ports so liquid flows into said first chamber and the outlet port registers with the other of the crosswise ports so liquid flows out of said second chamber and said valve member being movable to a second position in which the other of the inlet ports registers with the other of the crosswise ports so liquid fiows into said second chamber and the outlet port registers with said one crosswise port so liquid flows out of said first chamber, said inlet and crosswise ports communicating directly with the outlet port while the valve member is between said first and second positions, a free piston in said cylinder having a rod with a stop thereon, a bell crank lever pivoted on said body having one arm connected to said valve member and the other arm having a projection presented toward said stop on the piston rod and riding off the upper and lower edges of the stop respectively at the lower and upper ends of the piston stroke, a bar spring fixed at opposite ends to the piston rod and said valve member and bent by relative movement between the piston rod and valve memher in the direction to urge said projection toward said stop whereby the valve member is moved quickly at the end of each piston stroke to reverse the direction of flow to the piston, and means for counting the piston strokes to determine the volume of liquid flowing through the meter.

5. A liquid meter comprising a body having a cylinder open at both ends, means providing a first liquid filled chamber communicating with one end of the cylinder, means providing a second liquid filled chamber communicating with said other end of the cylinder, a slide valve member having one end presented to said first chamber and the other end presented to said second chamber, said valve member having between its ends two longitudinally spaced crosswise extending ports and a port extending longitudinally from said one end of the valve member to one of the crosswise ports, a port extending longitudinally from said other end of the valve'member to the other crosswise port, two longitudinally spaced inlet ways presented toward said valve member, an outlet way presented toward said valve member intermediate said inlet ways, said valve member being movable to a first position in which one of the inlet ports registers with one of the crosswise ports so liquid flows into said first chamber and the outlet port registers with the other of the crosswise ports so liquid flows out of said second chamber and said valve member being movable to a second position in which the other of the inlet ports registers with the other of the crosswise ports so liquid fiows into said second chamber and the outlet port registers with said one crosswise port so liquid flows out of said first chamber, said inlet and crosswise ports communicating directly with the outlet port while the valve member is between said first and second positions, a free piston in said cylinder, means for shifting the valve member successively to one and then the other of said positions at the end of successive strokes of the piston and means for counting the piston strokes to determine the volume of liquid flowing through the meter.

References Cited by the Examiner UNITED STATES PATENTS 111,624 2/1871 Fogarty 73251 1,266,417 5/1918 Davis 73251 1,534,238 4/1925 Mercer 73-251 2,860,513 11/1958 Cheronnet 73251 FOREIGN PATENTS 26,208 6/ 1920 Denmark.

1,121 3/ 1880 Great Britain.

RICHARD C. QUEISSER, Primary Examiner. 

1. A LIQUID METER HAVING A BODY WITH AN INLET, AN OUTLET AND A FREE PISTON IN THE FLOW PATH BETWEEN THE INLET AND OUTLET, SAID PISTON HAVING A PISTON ROD CARRYING A STOP, A REVERSING VALVE MOVABLE TO SUCCESSIVE POSITIONS FOR REVERSING THE FLOW TO THE PISTON, SAID VALVE HAVING BETWEEN SAID POSITIONS PORTS PROVIDING A DIRECT CONNECTION FROM THE INLET TO THE OUTLET, A VALVE OPERATOR SLIDABLE IN THE BODY PARALLEL TO THE PISTON ROD, A BELL CRANK PIVOTED ON THE BODY HAVING ONE ARM CONNECTED TO THE VALVE OPERATOR AND THE OTHER ARM HAVING A PROJECTION PRESENTED TOWARD SAID STOP AND RIDING OFF THE UPPER AND LOWER ENDS OF THE STOP RESPECTIVELY AT THE LOWER AND UPPER ENDS OF THE PISTON STROKE, A BAR SPRING EXTENDING BETWEEN AND FIXED AT OPPOSITE ENDS TO SAID VALVE OPERATOR AND SAID PISTON ROD AND BENT BY THE MOVEMENT OF THE PISTON ROD RELATIVE TO THE VALVE OPERATOR TO BUILD UP A FORCE FOR SHIFTING THE VALVE OPERATOR AT THE END OF EACH STROKE AND THEREBY REVERSING THE FLOW TO THE PISTON, AND MEANS ACTUATED BY THE PISTON FOR COUNTING THE PISTON STROKES AND THEREBY DETERMINING THE VOLUME OF LIQUID FLOWING THROUGH THE METER. 